For some reason I felt compelled to look up 1974 floods. This is because of a flood dream I had when I was three (see archives, Flood 1, 1974).
Strangely, I discovered that The Band did a live album in 1974 called Before the Flood. It was recorded in January and released in June.
I learned that there were at least three major floods on the record in 1974—this after a cursory search: one in Matewan, West Virginia (not far from where I was living in Pittsburgh), one in Brisbane, Australia, and one in Ashland, Oregon.
Also, FEMA provides a helpful fact sheet on floods and flash floods. Wish I had it when I was three.